Item not adding top cart Joomla 4 VM4

[petershaw54]

Hi, I have a problem with our new update to  Joomla 4 and Virtuemart with OPC. Our current but outdated site works well.
We have been unable to get VM to pass an item from the cart to OPC. This works fine in our end-of-life (VM3, J3) live site at brisart.org.

All information below relates to our VM4, J4 development site at devnew.brisart.org
We do not host the site ourselves so we cannot control the speed of the server for our development site.
PHP version is 8.1.26 - System Information below:

Setting     Value
PHP Built On     Linux au01.hostingbay.net 3.10.0-962.3.2.lve1.5.38.el7.x86_64 #1 SMP Thu Jun 18 05:28:41 EDT 2020 x86_64
Database Type     mysql
Database Version     5.7.44-cll-lve
Database Collation     latin1_swedish_ci
Database Connection Collation     utf8mb4_general_ci
Database Connection Encryption     None
Database Server Supports Connection Encryption     Yes
PHP Version     8.1.26
Web Server     Apache
WebServer to PHP Interface     litespeed
Joomla! Version     Joomla! 4.4.2 Stable [ Pamoja ] 9-January-2024 16:00 GMT



The issue may be related to sessions and/or cookies.

Clicking on the menu item Cart https://www.devnew.brisart.org/cart shows the cart as below:

This is Helium Outline - Cart
(I have hard coded the text above into the cart to show the source of the cart)
(The text below is being inserted automatically by Virtuemart - so the cart seems to be working.)
Cart
Cart empty
Back to Art Classes


However, adding an item (art course) to the cart fails at the point of registration and passing the item details to OPC:

Select a course from the home page e.g. https://www.devnew.brisart.org/courses/short-courses/painting-short-courses/pen-wash-2985

This loads the course information into VM.

Click on the Register Now button and the following popup appears:

_______________

Back to Art Classes Proceed with Registration

1 x Advanced Pen & Wash was added to your cart.
_______________

Click on the Proceed With Registration button, which has the same link to the cart as on the main menu at the top i.e. https://www.devnew.brisart.org/cart

and the cart cannot be found and importantly, the cart can also no longer be found using the main menu at the top.

The cart can only be activated again when the brisart cookies are deleted from the browser cache.

I need to resolve this before  we can develop plugin for Westpac bank in Australia.

[GJC Web Design]

here https://www.devnew.brisart.org/cart is a 404 when accessed from the top menu or the add to cart popup confirm